Process of dyeing polyolefins and other hydrophobic fibers



' rials.

United States Patent 3,252,749 PROCESS OF DYEING POLYOLEFENS AND OTHER HYDROPHOBIQ FEBERS Henry R. Mautner, Leonia, N..l., assignor to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Sept. 9, 1963, Ser. No. 307,361 Claims. (Cl. 8--55.)

The present invention relates to an improved process for dyeing polyolefinic fibers and other hydro-phobic mate- The invention has particular application to the dyeing of fabrics made of polypropylene fibers but it will be understood that it is applicable also to other polyolefin fibers and also to other fibers having generally similar properties and characteristics.

One of the most difficult problems involved in the development of new fiber textiles involves the development of satisfactory methods'which will be required for dyeing the fiber. It has often been necessary, whenever a new fiber is introduced, to devise entirely new dyeing methods. Sometimes new dyestuffs must be developed for the new fibers before they can be marketed successfully. Among the most promising new fibers which have been introduced in recent years are those made from polyolefinic materials such as, particularly, polyethylene and polypropylene. The stereo-regular polypropylenes, which are highly crystalline materials melting at temperatures in the range of about 165 to 172 0., present special problems in this respect. These fibers are particularly difiicult to dye because of their extreme hydrophobic properties. Difliculties in dyeing are due at least in part to the fact that their polyolefinic materials lack functional groups in their structure to which the dyes can attach. Because of these characteristics the dyeing of polypropylene fiber, in particular, has presented special problems. Particularly with respect to attempts to dye polypropylene fiber with vat dyestuffs, it has been found that the aqueous dyeing baths commonly used color the fiber only superficially. The dyestutf does not penetrate adequately inside the body of the fiber. Polyethylene fibers, and fibers of .copolymer type, present similar difilculties in varying degrees.

Other methods of dyeing such fibers have been attempted. Various suggestions have been made for modifying the dyeing bath by incorporating, for example, materials such as amines and the like as Well as other surface-active agents to improve the contacting between fiber and dye and to improve adsorption or adhesion of the dyestufi to the fiber.

Notwithstanding the various suggestions which have been made, attempts to dye polyolefins such as polypropylene fiber by conventional dyeing procedures generally have not been very successful. Hence it has been deemed necessary in the past to incorporate the dye or pigment directly into the plastic polypropylene before or during its extrusion into fibers, simply because other methods of dyeing were not satisfactory. This, of course, is an expensive procedure requiring, among other things, changes of color for each batch of fiber produced and requiring, of course, segregation and separate handling of fibers of different colors.

According to the present invention, it has been found that instead of using the conventional vat dyes, as these are employed in the vat dyeing process, dyeing of polypropylene and similar hydrophobic materials may be accomplished most successfully by use of the general procedures of vat dyeing, but replacing the vat dyes with basic dyes commonly used in an entirely different process. By the substitution of such dyes, and by employing par- 3,252,749 Patented May 24, 1966 is to obtain a water solution of the basic dye in a reduced form. Instead of sodium hydrosulfite other reducing agents may be used such as sodium borohydride. The alkaline agent may be sodium hydroxide, potassium hydroxide, ethanolamine, triethanolamine, ethylene diamine or tetraethylene pentamine. Preferably the alkaline agent and the reducing agent are combined in the same solution.

In the reduced state, the basic dyes, treated as indicated above, exhibit a marked afiinity for polypropylene and for other synthetic fibers which are normally hydrophobic. Good dyeings of deep color, which cannot be obtained by normal application or customary procedures, are obtained from solutions of the basic dyes treated as indicated and applied by vat dyeing methods.

In the practice of vat dyeing, the normal vat dyestuffs are ordinarily reduced with a combination of sodium hydroxide and sodium hydrosulfite. Generally speaking,

the vat dyestuffs will not give adequate reduction when treated with organic amines and, even if so treated and their reduction reasonably accomplished, they do not yield dyeings of quality as compared with those obtained by treatment of vat dyestuffs, in conventional vat processes, with sodinm hydroxide and sodium hydrosulfite.

By contrast, in the case of the reduced basic colors which are prepared and employing according to this invention, the selection of the alkaline agent may be governed by the requirements of the particular fiber which is to be dyed. Thus, certain fibers which may be damaged by the use of strong, caustic solutions such as sodium hydroxide or potassium hydroxide, may be dyed very satisfactorily with organic amines of suitable activity. Other fibers or fabrics, not injured by the caustic alkalies may be dyed by using the alkalies or by using suitable strong amines. In other words, the selection of the alkaline agent will be governed by the properties of the fiber. A procedure of this type cannot be adopted with regular vat dyes because the regular vat dyestuffs will not be sufficiently reduced by certain combinations of particular alkaline agents employed along with the reducing agent. In general, the alkaline agent will be either an alkali metal hydroxide, a water soluble amine, or mixtures of two or more of'these.

It will be understood that in vat dyeing, where the vat dye itself is water insoluble, the requisite solubility may be and normally is obtained by treating the dye with the hydrosulfite reducing agent plus the alkali in an aqueous medium. The water soluble reduced form of the dye may then be picked up by the fiber. After incorporation into the fiber the dye, in the conventional vat process, is oxidized either by air drying or by the addition of a suitable oxidizing agent. Hence, the dye incorporated in reduced form is oxidized back to the water insoluble colored dye form and it stays in the fiber, in the normal vat process. This particular technique, however, has not been used with basic dyes because it is not necessary for the dyeing of natural fibers with the latter type of dyestutf.

Prior to the present invention, apparently, it had not been understood that basic dyestuffs could be'reduced in a manner described above. However, even if it had been known that they could be so reduced, it is still surprising to find that they are reduced in the manner and to the degree accomplished by this invention. It appears even more surprising that the reduced form of the basic dye will attach itself to and penetrate into the body of the propylene fiber. It is unexpected, also, to find that it will stay on or in the fiber and remain an effective color former when oxidized back to the original basic dye.

A variety of basic dyestuffs may be used, for dyeing polyolefin fibers, according to the present invention. Such basic cationic dyestuffs as the diphenyl methane, triphenyl methane, xanthene, acridine, azine, oxazine and thiazine dyes are all capable of being used according to this process.

The invention has the further advantage that it offers a method for applying basic dyestuffs to synthetic fibers of other materials besides the polyolefin fibers which have presented difficulties in the past. Hence, these dyes can be applied to such materials as the acrylonitrile polymers, the polyamides, polyesters, and the like, wherever difiiculty has been encountered with conventional dyestuffs applied in conventional ways, especially if the hydrophobic characteristics of the fiber is a factor.

The particular process used for vat dyeing, as applied with basic dyes according to the present invention, may be varied in a number of ways known in the prior art. There are several general methods in practice for dyeing piece goods such, for example, as the pigment pad process, the pad steam process and the like. Any of these that are adaptable to conventional processes mayalso be applied in connection with the present invention.

The invention will be more particularly understood with respect to specific examples which will next be given. In addition to the fibers specifically mentioned above, those formed of cellulose triacetate, such as Arnel and others which are analogous may be treated by the same process. The oxidation which is to follow after the dyestuff has been incorporated in the fiber may be caused by air, by use of nitrous acid, or by use of hydrogen peroxide or other peroxides, persulfates, perborates, and the like as is well known to those skilled in the art.

Example 1 A aqueous dyebath was prepared with the following ingredients:

Genacryl Blue 36 (a Rensselaer product previously designated Rhoduline Pure Blue 36, Color Index 51,005) g 0.200 Diazopon SS-837 (a mixture of alkyl-phenol+ ethylene oxide in butyl cellulose) g 0.200 Ethylene diamine ml 3.00 NaOH, 30 B ml 1.00 Sodium hydrosulfite (Na S O g 1.50 Rongalite CX (sodium sulfoxylate) g 2.00

Sufficient water was added to make a final volume of 300 milliliters. Ten grams of polypropylene textile were introduced into the solution at 160 F. Thereafter the dye was raised to the boiling point and boiled 1 /2 hours. The oxidizing agent and soap were then added and the resulting fabric was colored a medium shade of blue with excellent results. Ratings of wash No. 3, perspiration resistance, dry cleaning resistance and crocking resistance were obtained. The light fastness was only fair, however.

Example 2 An aqueous dyebath of basic type was made by incorporating sufficient water to bring the final volume to 300 milliliters, using the following ingredients:

Methylene Blue JFA New (Rensselaer oxazine,

Color Index, CI 50,015) g 0.200 Diazopon SS-837 g 0.200 Ethylene diamine ml 3.000 Rongalite CX (sodium sulfoxylate) g 2.000 Sodium hydrosulfite g 1.500

4 As in the preceding example the polypropylene textile material was introduced into the bath at F., the solution raised to the boiling point, boiled 1 /2 hours, then oxidized and finished. A reddish, medium shade of blue was obtained having good wet fastness properties. The light fastness was fairly good.

Example 3 As in the preceding examples an aqueous dyebath was made by adding sulficient water to bring the final volume to 300 milliliters, using the following ingredients:

Sefranine Y ex. conc. (Rensselaer basic dyestuff,

CI 50,240) g 0.200 Diazopon SS-837 g 0.200 Rongalite CX (sodium sulfoxylate) g 2.000 Sodium hydrosulfite g 1.500

A 10 gram piece of solid polypropylene was entered into the solution at 160 F. The solution was then raised to the boiling point and boiled 1 /2 hours and finished by oxidizing as in the previous examples. A medium shade of pink was obtained having excellent wet fastness and fairly good light fastness.

The composition of Example 3, was used also to dye samples of Arnel, Dacron 54, Dacron 64 and Dynel. These materials were dyed with substantially the same results as the polypropylene of Example 3.

As those skilled in. the art will understand, various substitutions may be made for certain of the oxidizing and reducing agents and it is contemplated by the claims which follow to cover such variations as would suggest themselves to those skilled in the art as far as the prior art properly permits.

What is claimed is:

1. The process of dyeing polyolefinic fibers having hydrophobic properties which comprises, in combination, the steps of treating a basic dyestufr' selected from the group consisting of diphenylmethane, triphenylmethane,

- zanthrene, acridine, azine, oxazine and thiozine dyes with an aqueous solution of sodium hydrosulfite and an alkaline agent selected from the group consisting of alkali metal hydroxides, water-soluble organic amines and mixtures thereof, introducing the fabric into the treated dyestuff as reduced by said treatment, maintaining the dyestulf at a sufiiciently high temperature and for a time sufficient to obtain substantial penetration of the body of the fibers by said dyestuff, and thereafter oxidizing the dye to obtain fast colored dyed fibers.

2. A process according to claim 1 wherein the fiber is polypropylene.

3. A process according to claim 1 wherein the basic dyestuff is a diphenylmethane base dye.

4. The process according to claim 1 wherein the basic dyestutf is a triphenylmethane base dye.

5. The process according to claim 1 wherein the basic dyestulf is a xanthene base dye.

6. The process according to-claim 1 wherein the basic dyestufi is an azine base dye.

7. The process according to claim 1 wherein the basic dyestutf is an oxazine base dye.

8. The process according to claim 1 wherein the basic dyestufi is a thiazine base dye.

9. The process of dyeing a fabric of hydrophobic synthetic fibers and the like which comprises, in combination, the steps of treating a basic dyestuff selected from the group consisting of diphenylmethane, triphenylmethane, zanthrene, acridine, azine, oxazine and thiozine dyes with an aqueous solution of a reducing agent and an alkaline agent selected from the group which consists of alkali metal hydroxides, water soluble amines, and mixtures thereof to reduce said dyestuff to a water soluble stage, dyeing the fabric in absence of oxidation, and subsequently oxidizing to set the dye in the fabric.

10. In a process for dyeing hydrophobic synthetic fibers, fabrics and the like, the steps, in combination,

of first reducing a basic dye selected from the group consisting of diphenyl methane, triphenyl methane, xanthene, acridine, azine, oxazine, and thiozine dyes, by mixing said member with sodium hydrosulfite and an alkaline agent selected from the group consisting of alkali metal hydroxides, water-soluble organic amines and mixtures thereof, placing the fiber in an aqueous solution of such dye, heating the solution to a temperature of at least 160 F. for a period of time equivalent to at least one hour, in the absence of oxidizing material to incorporate the dye into the fiber and thereafter oxidizing the reduced dye in the fiber to obtain a fixed colored product of good dye penetration.

References Cited by the Examiner UNITED STATES PATENTS 3,127,231 3/1964 Neale 8-34 3,122,409 2/1964 Bardt 834 5/1964 Bonvicini et al. 8-115.5

' OTHER REFERENCES Knight: Manual of Dyeing, 9th ed., vol. 2, 1945, pp. 456-458, Mapleton House Publishers.

NORMAN G. TORCHIN, Primary Examiner.

THOMAS J. HERBERT, Assistant Examiner. 

1. THE PROCESS OF DYEING POLYOLEFINIC FIBERS HAVING HYDROPHOBIC PROPERTIES WHICH COMPRISES, IN COMBINATION, THE STEPS OF TREATING A BASIC DYESTUFF SELECTED FROM THE GROUP CONSISTING OF DIPHENYLMETHANE, TRIPHENYLMETHANE, ZANTHRENE, ACRIDINE, AZINE, OXAZINE AND THIOZINE DYES WITH AN AQUEOUS SOLUTION OF SODIUM HYDROSULFITE AND AN ALKALINE AGENT SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDES, WATER-SOLUBLE ORGANIC AMINES AND MIXTURES THEREOF, INTRODUCING THE FABRIC INTO THE TREATED DYESTUFF AS REDUCED BY SAID TREATMENT, MAINTAINING THE DYESTUFF AT A SUFFICIENTLY HIGH TEMPERATURE AND FOR A TIME SUFFICIENT TO OBTAIN SUBSTANTIAL PENETRATION OF THE BODY OF THE FIBERS BY SAID DYESTUFF, AND THEREAFTER OXIDIZING THE DYE TO OBTAIN FAST COLORED DYED FIBERS. 